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2 Sheets-Sheet 1. H;Q0LBY Altitude Instrument. N0.100J19. Patented Peb.22,187oj E @www N. PETiRs. Pxmmuxnngmpher. Vwashingwm D. C,

i 2 sheets-sheef-z. H. C 0L B Yv Altitude Instrument.

No. 100,119.v Patented Feb. 22,1870. 1 52%? E .w @l

-IW /I m I W initeil tatrs @sind @with HALL OOLBY OF NEVIT YORK, N. Y., ASSIGNOR TO HIMSELF AND GEORGE` G. OOLBY, OF WASHINGTON, DISTRICT OF COLUMBIA.

Letters Patent No. 100,119,.latecl February 22, 1870.v

IMPROVEMENT IN ALTITUDE INSTRUMENT The Schedule referred to in these Letters Patent and making part of the siamo.

To all whom it may conce/ru Figure 2, plate 1, is a sectional view of the instru` ment, showing the stop-lock and catch.

Figure 3, plate 2, is a view of the back of the instrument.

Figure 4, plate 2, is a vertical section, taken transversely through the center of the instrument.

Similar letters of reference indicate corresponding parts in the several figures.

The object of this invention is to construct an instrument which shall be simple and readily adjustable, and by means of which a correct altitude of' the sun, moon, or stars, or the altitude of terrestrial objects can be readily determined, notwithstanding the natural horizon may be obscured.

My invention is especially adapted for `iinding the correct position, of a ship at sea, when other instruments cannot be used, on account of a fog or darkness obscur-ing the horizon. To this end I have adapted the improved instrument to indicate both altitude and zenith at the Sallie time, and to do away with the usual corrections, such as dip, parallax, and retraction, and semi-diameter. I have also so constructed the instrument that it can be readily tested for determining its accuracy at any time, als will be hereinafter explained.

The following description will enable others skilled in the art to understand my improved instrument.

In the accompanying drawings- A represents what I denominate a graduated doublevernier balance, which is suspended from an axis, c, so as to swing freely, and which is graduated atg g', so as to form a double-Vernier, including an'ai'c of ninety degrees. lhis double-Vernier balance is suspended from bearings, which are applied to the frame G of the instrumenarat the back of which frame is a handle, J, by which the instrument is held while taking an observation.

'lhe frame G has a flange, G', formed on its perimeter, the face of which is marked ofi', so as to present' This graduated arc is surmo'unted bya horizon-plate or level, b, which is in a plane at right angles to a plane intersecting the axis c and Cypher-mark on the arc of 1800.

This horizon-plate bis provided with a spirit level, P, shown in iig. 4, which is used for determining the accuracy of the instrument in the following manner:

If, when the bubble of the spirit level indicates that the plate b is horizontal, the arrow on the face of the lower 'li-mb of the double-Vernier balance points to the cypher on the arc of' 180, as indicated in tig. 1,.t hen it is known that the instrument is properly adjusted for observation.

On the horizon-plate b I secure a telescope, which is composed of two tubular sections a a2, applied one at each extremity of the said plate, and adjusted so that their axes coincide and are in a plane parallel with the plate b. flhe tubes a a2 have no lenses in them, but are provided with crossed wires and inesightingplates. The cross-Wires are applied in the tube a, and the sighting-plates are applied in the tube a.

By thus constructing the telescope of two separated sections, an object can` be more readily found. than in.

any othermanner.

lhe lower limb of the double-Vernier balance A is c, as shown in iig. 1.

The tension which is thus produced will prevent the double-Vernier balance from being too sensitive to vibration, without interfering with its accuracy asa bal anced Vernier in the use ot' the instrument.

Beneath the double-Vernier balance A and pivoted to a stud, o, is a level', O, carrying on one 'end a bevelcd locking-tooth, a, which passes through and is guided by the bottom of the frame G, asshown in iig. 2. v

A spring, s, is applied to frame G, so as to act upon O, and press the tooth a upwardly and lock the frame andvernier balance, and thus allow the angles which have been found by observation through the telescope to be read olf on the scale f f g g.

The lever and tooth are set by means of a-trigge-r, 71, which is applied on'the end ofa spring, i, as shown in fig. 2. When the lever C is held up by the trigger, as shown in fig. 2, the Vernier A and frame G are releasedfrom tooth a, and the instrument is adjusted for use. i

It will be seen from the above description that the improved instrument has a geocentric balance with an arc otl 900, and with two verniers 900 apart, so'arranged that the altitude Vernier rests at the center or nadir, 0, of the arc of 1800, when the zenith Vernier points to the 900 mark (or plane of the telescope) on the arc G', by which means the correct altitude can be taken ofthe sun, moon, planets, `or stars, or of any elevated terrestrial object.

ions on thc vernier are indicate degrees and half degrees, by which the vernier reads to miles, (or minutes.) Thus, thirty divisions on a Vernier scale cover tweuty-nine divisions on the arc of 1800.

Having described my invention,

What I claim as new, and desire to secure by Letters Patent, is-

1. Au instrument for determining,r at the same time both the altitude and zenith distance of celestial or terrestrial objects, which consists ofthe arc G ot' 1800, a level, P, a horizon-plate, b, telescope a [12a-nd a double-Vernier balance, A, in combination with a stoplock or catch, substantially as described.

2. The combination with the Vverljer balance A of a tension-device, consisting of tension-springs d (I, cord e, and a pulley, d', substantially as described.

XVitnesses: HALL GOLBY.

R. T. CAMPBELL, J. N. CAMPBELL. 

